Biology Chapter 2 Flashcards
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Questions and Answers

Does all life require the same essential elements?

False

Which of the following is a chemical reaction?

  • Making a hydrogen bond between a water molecule and a sugar molecule
  • Dissolving a lump of sugar in a cup of coffee
  • Melting ice
  • None of the above (correct)

    • What is the BEST explanation of what has occurred when Carbon-14 decays?

  • An ionic bond has formed
  • The resulting atom is still carbon-14
  • The resulting atom still has an unstable nucleus
  • The resulting atom is now a different element because the number of protons has changed (correct)

    • What happens when two atoms form a chemical bond?

    <p>A chemical bond forms when two atoms transfer or share outer electrons to complete their outer shells</p> Signup and view all the answers

    What do you predict to be the charge on ammonium?

    <p>+1</p> Signup and view all the answers

    How many electron pairs are shared between carbon atoms in a molecule that has the formula C2H2?

    <p>3</p> Signup and view all the answers

    What is a compound?

    <p>Compounds have at least two different elements.</p> Signup and view all the answers

    Which bond or interaction would be difficult to disrupt when compounds are put into water?

    <p>Covalent bonds between carbon atoms</p> Signup and view all the answers

    Cations have a _________ charge and anions have a _________ charge.

    <p>cation = positive; anion = negative</p> Signup and view all the answers

    A covalent bond is likely to be polar when:

    <p>One of the atoms sharing electrons is more electronegative than the other atom</p> Signup and view all the answers

    Define electronegative.

    <p>High tendency to attract electrons to itself.</p> Signup and view all the answers

    Define element.

    <p>Substance that cannot be broken down into a simpler substance by ordinary chemical reactions.</p> Signup and view all the answers

    Define essential elements.

    <p>The elements an organism needs to live and reproduce.</p> Signup and view all the answers

    Define trace elements.

    <p>Elements required by an organism in minute quantities.</p> Signup and view all the answers

    What is carbon's atomic number and mass number?

    <p>Atomic number = 6, mass number = 12</p> Signup and view all the answers

    What is an allotrope?

    <p>Different physical forms of the same element.</p> Signup and view all the answers

    What is oxygen's atomic number and mass number?

    <p>Atomic number = 8, mass number = 16</p> Signup and view all the answers

    Define atom.

    <p>The smallest unit of an element that still retains the properties of that element.</p> Signup and view all the answers

    What does the atomic number tell you?

    <h1>of protons</h1> Signup and view all the answers

    What does the mass number tell you?

    <h1>of protons + neutrons</h1> Signup and view all the answers

    Define ion.

    <p>Atom with a net electric (+ or -) charge.</p> Signup and view all the answers

    Define isotope.

    <p>Atoms of the same element that differ in the # of neutrons.</p> Signup and view all the answers

    Define radioisotopes.

    <p>An isotope that has an unstable nucleus.</p> Signup and view all the answers

    What is radiocarbon dating - C14 used for?

    <p>Used to estimate large time scale ages.</p> Signup and view all the answers

    The first electron shell can hold ___ electrons, the second and third electron shells can hold ___ electrons.

    <p>1st shell = 2; 2nd and 3rd shell = 8</p> Signup and view all the answers

    What is the valence shell?

    <p>The outermost shell, determining the chemical properties.</p> Signup and view all the answers

    What is a valence number?

    <p>The number of electrons needed to be lost or gained to be stable.</p> Signup and view all the answers

    Define molecule.

    <p>Two or more atoms from same or different elements held together by valence shell electron interaction.</p> Signup and view all the answers

    When electron shells are full, atoms are ________.

    <p>Stable</p> Signup and view all the answers

    When electron shells are not full, ______________ occurs.

    <p>Interaction</p> Signup and view all the answers

    What are the three types of chemical bonds?

    <p>Ionic, covalent, hydrogen.</p> Signup and view all the answers

    Define ionic bonds.

    <p>Atoms bonded through attraction of oppositely charged particles (ions) - exchange of electrons.</p> Signup and view all the answers

    Define covalent bonds.

    <p>Atoms share valence electrons.</p> Signup and view all the answers

    Define polar covalent bonds.

    <p>Unequal sharing, causing a slight electrical dipole.</p> Signup and view all the answers

    Define non-polar covalent bonds.

    <p>Equal sharing; the charge is the same on both atoms.</p> Signup and view all the answers

    Any bond between two atoms of the same element forms a _________ bond.

    <p>Non-polar covalent bond</p> Signup and view all the answers

    Define free radical.

    <p>A molecule whose atoms have one or more unpaired electrons in their outer shells.</p> Signup and view all the answers

    What can you do to prevent free radical damage?

    <p>Take vitamins A and E and use antioxidant cream.</p> Signup and view all the answers

    Define hydrogen bonds.

    <p>Formed when partially positive hydrogen atoms in polar covalent bonds are attracted to partially negative atoms in another polar covalent bond.</p> Signup and view all the answers

    Are hydrogen bonds strong?

    <p>False</p> Signup and view all the answers

    List the three chemical bonds (ionic, hydrogen, and covalent) in order from strongest to weakest.

    <p>Covalent &gt; Ionic &gt; Hydrogen</p> Signup and view all the answers

    Chemical bonds hold _________________ together and store __________.

    <p>Molecules, energy</p> Signup and view all the answers

    Chemical equations describe _____________ ____________.

    <p>Chemical reactions</p> Signup and view all the answers

    In a chemical equation, reactants are written to the _______ of the arrow and products are written to the _______ of the arrow.

    <p>Reactants on the left, products on the right</p> Signup and view all the answers

    Define oxidation.

    <p>Chemical process in which an atom, molecule, or ion loses an electron(s).</p> Signup and view all the answers

    Define reduction.

    <p>Chemical process in which an atom, molecule, or ion gains an electron(s).</p> Signup and view all the answers

    An example of an oxidation-reduction reaction is ____________.

    <p>Rusting</p> Signup and view all the answers

    Two examples of redox in biological systems are _________ and __________ _____________.

    <p>Glycolysis and cellular respiration</p> Signup and view all the answers

    Study Notes

    Essential Concepts in Chemistry

    • All living organisms require essential elements, but not all share the same elements.
    • A chemical reaction involves changes in molecular structure, unlike processes like dissolving or melting.

    Carbon-14 and Nuclear Transitions

    • Carbon-14, with 6 protons and 8 neutrons, is pivotal in carbon dating.
    • When a neutron converts to a proton, it changes the atom's identity, indicating a transformation into a distinct element.

    Chemical Bonds

    • Atoms form chemical bonds by transferring or sharing outer electrons to achieve stable configurations.
    • Nitrogen, typically forming three bonds, has a +1 charge in ammonium due to forming four bonds with hydrogen.

    Covalent and Ionic Bonds

    • Carbon in C2H2 shares three pairs of electrons through covalent bonds.
    • Covalent bonds, particularly those between carbon atoms, are resistant to disruption in water.
    • Cations carry a positive charge, while anions carry a negative charge.

    Bond Polarities

    • A covalent bond becomes polar if one atom is more electronegative than the other, leading to an unequal sharing of electrons.
    • Electronegativity refers to an atom's tendency to attract electrons.

    Elements and Structures

    • Elements cannot be broken down by ordinary chemical reactions and have unique properties, defined by their atomic structures.
    • Essential elements like oxygen, carbon, hydrogen, and nitrogen are crucial for life, while trace elements are needed in minute quantities.

    Atomic Structure and Isotopes

    • The atomic number indicates the number of protons, and the mass number combines protons and neutrons.
    • Isotopes of an element differ in neutron count, with unstable radioisotopes undergoing decay.

    Chemical Stability and Valence

    • Atoms are stable when their electron shells are full; interactions occur when they are not.
    • The valence shell determines an atom's chemical properties, and the valence number indicates electrons needed for stability.

    Types of Chemical Bonds

    • Chemical bonds include ionic, covalent, and hydrogen bonds, arranged from strongest to weakest as: covalent > ionic > hydrogen.
    • Ionic bonds result from the attraction of oppositely charged ions, while covalent bonds involve shared electrons.

    Molecular and Atomic Interactions

    • A molecule comprises two or more atoms held together by electron interactions.
    • Free radicals, which have unpaired electrons, are unstable and reactive, leading to potential cellular damage.

    Reactions and Equations

    • Chemical equations depict reactions, with reactants on the left and products on the right.
    • Oxidation involves losing electrons, while reduction refers to gaining electrons. An example of a redox reaction is rusting.

    Biological Significance

    • Processes like glycolysis and cellular respiration demonstrate oxidation-reduction reactions in biological systems, highlighting their importance in metabolism.

    Protective Measures

    • To combat free radical damage, antioxidants such as vitamins A and E can be beneficial.

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    Test your knowledge on the essential elements of life and chemical reactions with these flashcards from Biology Chapter 2. Challenge yourself with questions about Carbon-14 and its use in dating. Perfect for students looking to reinforce their understanding of biological concepts.

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